is needed to determine the size of a light-trap catch necessary to indicate an economically 

 damaging or potentially damaging infestation present in the area. 



The ultimate extent to which light traps can be useful in predicting the need for 

 control is limited only by the number of insect species of economic importance which 

 are nocturnal and positively phototropic. 



THE USE OF ELECTRIC LIGHT TRAPS AS AN INSECT CONTROL 1 



Howard O. Deay 2 



The use of electric light traps as an insect control is still in the experimental stage. 

 Much basic research needs to be done by entomologists and agricultural engineers on 

 this problem. However, the results of cooperative experiments conducted in Indiana by 

 the Purdue Departments of Entomology and of Agricultural Engineering and the Farm 

 Electrification Branch of the ARS indicate that satisfactory controls of certain insect 

 species can be obtained with existing, commercially available light sources. 



The use of light traps to protect plants from insects is based on the phototactic 

 response of the adults. This response may be either positive or negative. Our work at 

 Purdue on the control of agricultural pests has been concerned for the most part with 

 the photopositive response. The controls may be either preventive or remedial. If pre- 

 ventive, the light traps must be installed and functioning before the adults deposit their 

 eggs or injure the crops. 



Not all species of insects are phototactic, therefore, it is self-evident that light traps 

 will not be a panacea for all injurious insects in the field and that other types of insect 

 control will be needed. 



Some of the problems and/or disadvantages associated with the use of light traps as 

 a control tool at present are: (1) The availability of electric power, (2) initial cost of 

 the light traps, (3) the cost of field installations, (4) the destroying of the insects attracted 

 to the traps, and (5) the accurate evaluation of the results obtained. 



The major factors in the successful use of light traps for control are: (1) The "in- 

 tensity" and power of the light source and the wavelengths of energy emitted, (2) the 

 design of the trap and the location and spacing of the traps in the field, and (3) the 

 physiology, ecology (especially the effects of the physical factors of the environment on 

 the flight and phototactic response of insects), morphology, and life history of the insect 

 species in question. 



Some of the possible uses of light traps as an insect control are, as follows: 



1. To protect growing plants from larvae and nymphs, by destroying the adults 

 before they have mated or the females have deposited eggs, and from injurious 

 adults. 



2. To serve as a supplement to other types of insect control. 



3. To control certain species of insects that have become resistant to insecticides. 



1 Journal Paper No. 1716 of the Purdue University Agricultural Experiment Station, Lafayette, Ind. 



2 Professor of Entomology, Department of Entomology, Purdue University Agricultural Experiment Station, Lafayette, Ind. 



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